 where \(U\) ,\(U_B\) , \(u\)  and \(\nu \)  are the Dirac spinors of the proton, and the baryon in the fluctuated state, the quark and the antiquark inside the meson, respectively. \(k\)  and \(r\)  denote the momenta of the antiquark and the meson, with \(x\)  and \(y\)  representing their light-cone momentum fractions.
The indices \(\lambda _N\) , \(\lambda _B\) , \(\lambda _q\) , \(\lambda _{\bar{q}}\)  denote the helicity of the proton, the baryon, the quark and sea quark, respectively.
To evaluate Eq. (REF ), we apply the conventions in Refs. [1]}, [2]} for the spinors (in the case of quark and antiquark):
\(&u(k,+)=\frac{1}{\sqrt{2^{3/2}k^+}}\begin{pmatrix}\sqrt{2}k^++m\\k_1+ik_2\\\sqrt{2}k^+-m\\k_1+ik_2\\\end{pmatrix},  \\&u(k,-)=\frac{1}{\sqrt{2^{3/2}k^+}}\begin{pmatrix} k_1+ik_2\\\sqrt{2}k^++m\\k_1-ik_2\\\sqrt{2}k^+-m\\\end{pmatrix}, \\&\nu (k,+)=\frac{1}{\sqrt{2^{3/2}xr^+}}\begin{pmatrix}\sqrt{2}xr^+-m\\k_1+ik_2\\\sqrt{2}k^++m\\k_1+ik_2\\ \end{pmatrix}, \\&\nu (k,-)=\frac{1}{\sqrt{2^{3/2}k^+}}\begin{pmatrix}-k_1+ik_2\\\sqrt{2}k^+-m\\k_1-ik_2\\ \sqrt{2}k^+-m\\ \end{pmatrix}, \) 
